Integrated circuit test power supply
A power supply for testing an integrated circuit includes a source voltage input terminal for receiving an input voltage. The power supply serves as both a DUT active power supply and an IDDQ measurement circuit, without the need for switching between separate DUT active power supply and IDDQ measurement circuits. In one embodiment, a current source output driver includes a diode across a current sensing resistor inside a feedback loop. This minimizes VDD changes when the DUT demands transient current, such as when loading IDDQ test vectors. Moreover, with decreased transient changes in VDD, dielectric absorption effects of a decoupling capacitor are reduced.
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Claims
1. A power supply for testing an integrated circuit, comprising:
- a source voltage input terminal;
- an operational amplifier coupled to said input terminal and configured to produce current in response to a feedback signal;
- a shunt resistor coupled to said operational amplifier;
- a diode coupled in parallel with said shunt resistor;
- a current sensor coupled in series with said shunt resistor; and
- an output terminal coupled to said resistor, diode and current sensor, said output terminal configured to connect to a device under test.
2. The power supply of claim 1, further comprising a second operational amplifier positioned between said first operational amplifier and said shunt resistor.
3. The power supply of claim 1, further comprising one end of a decoupling capacitor coupled to said diode between said diode and a device under test, and an other end of said decoupling capacitor coupled to a reference voltage, which may be ground.
4. The power supply of claim 1, further comprising an analog to digital converter coupled to said current sensor and configured to generate a digital signal representative of an analog input signal.
5. A precision measurement power supply, comprising:
- a source voltage input terminal;
- an operational amplifier coupled to said input terminal and configured to produce current in response to a feedback signal;
- a shunt resistor coupled to said operational amplifier;
- a diode coupled in parallel with said shunt resistor;
- a current sensor coupled in series with said shunt resistor; and
- an output terminal coupled to said resistor, diode and current sensor, said output terminal configured to connect to a device under test.
6. The power supply of claim 5, further comprising a second operational amplifier positioned between said first operational amplifier and said shunt resistor.
7. The power supply of claim 5, further comprising one end of a decoupling capacitor coupled to said diode between said diode and a device under test, and an other end of said decoupling capacitor coupled to a reference voltage, which may be ground.
8. The power supply of claim 5, further comprising an analog to digital converter coupled to said current sensor and configured to generate a digital signal representative of an analog input signal.
Type: Grant
Filed: Sep 29, 1995
Date of Patent: Jun 30, 1998
Assignee: Megatest Corporation (San Jose, CA)
Inventors: Jan B. Wilstrup (Mounds View, MN), Stanley Peter Mros (Roseville, MN)
Primary Examiner: Vinh P. Nguyen
Law Firm: Flehr Hohbach Test Albritton & Herbert LLP
Application Number: 8/536,206
International Classification: G01R 1512;